Sensitive relay



April 7, 1959 A. E. SPRANDo SENSITIVE RELAY Filed July 12, 195e HEL-N7- SENSITIVE RELAY Anthony E. Sprando, Portland, Greg., assignor to Iron Fireman Manufacturing Co., Portland, Oreg.

Application July 12, 1956, Serial No. 597,545

13 Claims. (Cl. 200-87) This invention relates generally to electric relays of the type in which a small amount of electric energy is i fed to an electric coil to energize a magnetic circuit to actuate an armature to move a biased switch blade to close an electric circuit.

More particularly this invention relates to such relays which require a minimum of operating power, which are highly resistant to damage from shock or vibration and remain operative as calibrated over a wide temperature range.

A primary object of this invention is to provide a relay of small size and extreme sensitivity which will be reliably operable even though subjected to extreme mechanical shock or vibration of high amplitude or high frequency or both or to operation over an extreme temperature range. f It is a second object to provide such a relay with a magnetic circuit highly effective in transforming the electric energy of the operating coil to magnetic torque on the armature in order that the relay will be highly sensitive.

It is a third object to provide such a relay with an armature of low mass and mounted for rotary motion about its center of gravity in the plane of said rotary'motion.

It is a fourth object to preload the magnetic circuit of the relay mechanically into the hermetically sealed container for the relay so that the shape of the magnetic circuit under shock or vibration may not be changed without positive distortion of the container,

It is a lifth object to provide such a relay having a magnetic circuit including two air gaps in Series, each of the air gaps being of great area in a plane normal to the iiux path and with minimum length of ux path.

It is a sixth object to provide such a relay with a magnetic circuit having two parallel magnetic pole faces widely spaced in the direction parallel to said pole faces and narrowly spaced in the direction normal to said pole faces together With an armature having similar pole faces similarly spaced, the armature being pivoted to rotate on an axis through its center of gravity and normal to the two directions of displacement of its parallel pole faces.

' It is a seventh object to provide such a relay with means for limiting the minimum length of its air gaps to which said armature may be thrown when its magnetic circuit is energized.

It is an eighth object to provide such a relay with means for limiting the maximum length of its air gaps to which It is a tenth object to provide such a relay having means for limiting the lost motion with respect to the free end of a resilient switch blade of a lost motion driver therefor to prevent oscillatory transfer of kinetic and potential energy between the blade and the driver and thus sup-` press the development of contact bounce by the blade.

How these and other objects are attained are explained in the following description referring to the attached Fig. l is a side sectional elevation with parts broken away to show other parts taken along one of the diagonals of the square container of the relay of this invention.

Fig. 2 is a side elevation in partial section taken along the other diagonal of the square container of the relay of this invention.

Fig. 3 is a plan sectional view along the line 3-3 of Fig. 2.

Fig. 4 is a plan view in 4 4 of Fig. 2.

Fig. 5 is a fragmentary view in elevation along the line partial section along the line s s of Fig. 4.

said armature can be thrown by its biased switch blade I when its magnetic circuit is de-energized.

It is a ninth object to provide such a relay having a relatively stationary contact and a movable contact biased toward said stationary contact by a resilient blade having one end stationary and the other end loosely engaged Like reference numerals refer to like parts in the several figures of the drawing.

Referring now to the drawing there is shown a drawn sheet aluminum container 11 square in plan section, open at the bottom and with a pair of symmetrically placed turrets 12 formed to extend upwardly from its closed top end 13. Closing the open bottom end of container 11 is a cupped base 14 having a hollow cylindrical extension 15 formed axially downwardly from the end 16 thereof. A circular hole 17 is formed through the bottom of eX- tension 15 through which are rigidly supported in a rigid insulating ceramic matrix eight symmetrically placed relay terminals like 18 to which the eight wires leading to the relay electrical circuit parts are connected within the base 14. Hole 19 formed through the bottom of base 14, see Fig. 2, is for the purpose of filling the container with inert gas after the relay is completely assembled therein. Relay mounting screws and 101 are symmetrically secured in diagonal corners of base 14 as shown.

The magnetic circuit of the relay comprises a pairfof substantially identical electrical steel pole pieces, 20 and 21, a bottom end yoke 22 and an armature 23. Electrical steel yoke 22 is formed with a flat top and four spaced legs extending downwardly at a right angle thereto as shown. The outer flat faces of the legs of yoke 22 are spaced to mate tightly respectively with the inner four faces of cupped base 14 so that yoke 22 is securely held against lateral movement in base 14.

Each of the pole pieces 20 and 21 are seen to be formed with a relatively large rectangular pole face section 24, with round sections 25 and 26 extending upwardly and downwardly respectively therefrom and separated from section 24 by flat sided sections 27 somewhat larger in end diameter than round sections 25 and 26 which are of the same diameter as the thickness of section 24. As shown in Fig. 1 the lower ends of pole pieces 20 and 21 are reduced in diameter at 28 and set through holes formed in yoke 22 where they are securely riveted in place.

As shown in Figs. 3, 4 and 5, armature 23 is formed of a rectangular sheet of electrical steel with journal extensions 29 extending from the top and bottom edges thereof in alignment axially through the center of gravity of a horizontal section thereof. Extensions 29 are formed with reduced diameter journal ends thus leaving end bearing shoulders 30 inside the journal ends.

Non-magnetic metal bearing plates 31 and 32 are required angularly mechanically to secure the pole face section of pole pieces 20 and 21 rigidly in place and also I to form the bearing supports for armature journals. Bear- Patented Apr. 7, 1959.

' 3 ing plates 31 and 32 are each formed with central bearing holes rotatably to receive armature journals 29 and with symmetrically spaced holes to receive the round ended, fiat sided sections 27 of pole pieces 20 and 21. I t should vbe. noted that as shown in Figs.y 3 and 4 the holes formed in plates 31 and 32 to receive sections 27 of pole pieces 20 and 21 are oriented so that diagonally positioned pole faces of armature 23 will parallelly abut their mating pole faces on sections 24 of pole pieces 20 and 21. y

y Surrounding pole pieces 20 and 21 between plate 32 and yoke 22 are electrical solenoid coils 33 and 34 for energizing the magnetic circuit.

l The assembly sequence for the magnetic circuit is as follows. Bearing plate 31 is placed upside down i-n a jig adapted for the purpose and pole pieces 20 and 21 areplaced upside down with their extensions 25 through their respective receiving holes in plate 31. Sections 27 of pole pieces 20 and 21 are oriented to mate with the holes in plate 31. Armature 23 is then placed in position between pole piece sections 24 with one of its journals 29 in the journal bearing hole in plate 31. End play adjustment spring washer 35, see Fig. 5, is then placed over the other armature journal 29 and the other bearing plate 32 is threaded over pole piece sections 26 and onto pole piece sections 27 and the other ybearing journal 29. A relatively heavy pressure is then used to force plates 31 and 32 over sections 27 of pole pieces 20, 21 to secure this part of the assembly with a press fit. Coils 33, 34 are then assembled over sections 26 of pole pieces 20, 21 and yoke 22 is assembled over the ends 28 of pole pieces 2i), 2l.. The ends 28 of pole pieces 2i), 21 are then riveted securely over yoke 22 and the magnetic circuit is assembled.

The relay here disclosed has a circuit switching mechanism which includes a pair of single pole double throw switches mounted respectively on insulating boards 36, 37 secured as shown on ears 38 of bearing plates 31, 32 which extend through holes appropriately formed in boards 36, 37 and are then riveted over to hold boards 36, 37 securely in place. To each of the insulating boards 36, 37 are riveted, as shown, a pair of similar stationary Contact brackets 39, 40 each adjustably supporting a stationary contact 41, 42 and connected by wires 43, 44 to a respective one of the relay terminals 18. Also to each of the boards 36, 37 are riveted, as shown, a blade bracket 45 to which is secured one end of resilient electrically conducting switch blade 46 carrying double switch contact 47. Brackets 45 are each connected :by wires 48 respectively to appropriate ones of terminals 18. Also coil brackets 49 riveted to insulating boards 36, 37, respectively are respectively connected pling of thev bifurcated gaps and move armature 23, driver 53 and switch blades 46 to move movable contacts 47 away from stationary contacts 41 and into contact position with stationary contacts 42.

Adjustable screw 55 threaded through section 24 of pole piece 20 is positioned in nal adjustment of the relay to prevent the pole faces of armature 23 from coming into actual contact with the pole faces of pole pieces 20, 21 when the relay is energized and further to adjust the minimum spacing of the pole faces for :best operation of driver 53 to reduce the bounce of contacts 47 on contacts 42. Adjustable screw 56 threaded through insulating board 37 is positioned in final adjustment just to contact armature 23 when the relay is un-energized and armature 23 has settled into' a stationary position without hindrance. Screw 56 and its use is an important part of this invention for together when the loose couends of driver 53 with blades 46 it prevents the uncontrolled oscillatory transfer of the alternating kinetic and potential energy of the blade and driver system which without this type of connection and control thereof would disastrously bounce contacts 47 on contacts 41 at some shock frequencies.

When the internal operating structure of the relay rnechanically supported on the magnetic circuit is assembled and adjusted it is set into container base 14 with the outer faces of the four legs of yoke 22 mating with a push iit the respective inner four faces of the base 14. The two each of wires 43, 44, 48 and 51 connected to the eight. terminals 18 are then connected as shown to the two each of brackets 39, 40, and 49 appropriately. Container 11 is turned to sit on turrets 12 and the internal assembly is dropped into container 11 with sections 25 of pole pieces 2t), 21 resting on the inner end faces of turrets 12 and base 14 tting snugly into the open end of container 11. Then a pressure of several pounds is placed on the outside of base 14 to clamp the ends of the legs of yoke 22 and the ends of sections 25 of `pole pieces 20, 21 between the inner faces of turrets 12 of container 11 and the inner face of base 14. While thus held under pressure container 11 is soldered and hermetically sealed to base 14 as indicated at 57. The container is then lled with inert gas through hole 19 in base 14 to one end of coils 33, 34 by wires 50 and to one of the terminals 1S by wire 51. The other ends of coils 33, 34 are connected together, not shown.

Pinned to the top of armature 23, as shown at 52 in Fig. 4, is switch blade driver 53 each of whose bifurcated opposite ends straddle respectively one of the switch blades 46. Individual prongs 54 of each end of driver 53 are tipped with ceramic insulation material electrically to isolate the magnetic structure from the switch structure.

It is to be noted that resilient switch blades 46 bias movable contacts 47 toward contact with stationary contacts 41 in brackets 39 and also through driver 53 bias armature 23 rotationally about its journals 29 in the direction to separate the poles faces of armature 23 from the pole faces of sections 24 of pole pieces 20, 21. Then when coils 33, 34 in series are electrically energized through two of the terminals 18 and wires 51, 50, the magnetic circuit set up through yoke 22, pole pieces 20, 21 armature 23 and the two air gaps separating respectively the pole faces of armature 23 and sectionsl 24 of pole pieces 20, 21, will be energized to set up a torque couple in the Idirection to shorten the air and after proper marking of the container the relay is completed.

It is to be remembered that the novelty and utility of this relay rests in its great sensitivity together with its ability to resist becoming unreliable in operation due to high mechanical shock and vibration loads impressed on it from outside the container.

The resistance to deformation of the magnetic structure is assured by pivoting armature 23 on short journals axially aligned through its center 0f gravity in closely spaced bearing plates 31 and 32 press tted onto pole pieces 20, 21 whose other ends are riveted into heavy yoke 22 and then press tting this structure into container 11 and base 14.

Armature journals 29 are short strong stubs and by mounting armature 23 on an axis through its center of gravity they not only prevent the unwanted translation of the armature in the magnetic structure but also prevent shock or vibration from having any rotational eiect on the armature.

The only moving part of the relay which is not balanced about its center of gravity to cancel vibration or shock forces which might affect its reliable operation are the free ends of switch blades 46 carrying movable contacts 47. To prevent spurious movement, these blades and contacts are made as light weight -as possible but the blades are suiciently stiff, though resilient, to bias contacts 47 against contacts 41 with a force capable of resisting a shock force of 50 G, which might be applied to the relay in a direction to spuriously move contacts 47 away from contacts 41.

assnasi lf holding contacts 47 against contacts 41 were the only diflicult operational requirement this itself would not be difficult but to this requirement is added an opposite requirement that the relay must be very sensitive in operation which in some instances may mean that an electric energy input of as little as 6 one-thousandths of a watt must operate the relay without fail. To do this requires the magnetic circuit to be of such shape and material that at this small coil input the rotational forces on the armature must supply suiiicient torque for driver 53 to complete the operation of blade 46.

Therefore the disclosed magnetic circuit is uniquely constructed to accomplish a new result. To produce the greatest possible magnetic iiux through the magnetic circuit-with the small available magneto-motive force, after selecting the most desirable magnetic steel to be used as would normally be done, a shape of magnetic circuit had to be devised which would allow suicient movement of the armature and yet give sufiicient torque for operation of the relay. The present disclosure shows how this is accomplished in uniquely sizing and positioning the pole faces of the armature of the pole pieces. As previously noted the pole faces of section 24 of pole pieces 20, 21 are parallel; face in opposite directions; are displaced in a lateral direction normal to the axis of the armature and parallel to the pole faces; and are displaced in a direction normal to the axis of the armature and normal to the pole faces; the latter displacement being only slightly more than the thickness of armature 23 and the first displacement being such that the adjacent edges of the pole faces are separated approximately the thickness of one of the sections 24. In this arrangement the minimum length of the air gaps varies little and the length of the armature section carrying the total magnetic flux is substantially constant. As the armature rotates to move blade 46 against its inherent bias with the biasing force to lbe overcome increasing approximately in proportion to the linear movement of blade 46 or the angular movement of armature 23, the reluctance of the air gap decreases proportionately so that the required magnetic rotating force on the armature keeps ahead of the increasingly opposing biasing force inherent in spring blade 46.

Having provided a vibration and shock resistant relay which also requires only a minimum of operating energy it is also necessary for the relay to be able to operate reliably at high speed without contact bounce.

With the design as previously described using a strongly ybiased blade 46 to prevent shock displacement and a magneticoperating force carefully arranged to parallel the lbiasing force in amplitude as the blade is moved against its bias, as movable contact 47 is moved up to stationary contact 42; armature 46 is stopped by screw 55. Blade 46 held at one end by bracket 45 and at the other lby driver 53 positioned by armature 23 is strained over movable contact 47 pressed against stationary contact 42. y With a careful adjustment of screw 55 no appreciable bounce of contact 47 is experienced. In the other direction of operation of blade 46 when the electric circuit through coils 33, 34 is broken and the magnetic circuit suddenly de-energized there is nothing to restrain blade 46 which due to its inherent bias suddenly whips contact 47 away from contact 42 and toward contact 41. The end of blade 46 takes with it driver 53 and armature 23. In its position of contact of contact 47 on contact 42, due to its bias blade 46 has a relatively large stored potential energy which when the relay is de-energized is transferred to kinetic energy in blade 46 and armature 23 as the inherent bias of blade 46 moves the rotating system to its position of contact 47 in contact with contact 41. If screw 56 were not positioned to stop driver 53 and armature 23 from overthrowing after contact 47 hits contact 41 and taking with driver 53 the end of blade 46, the more or less freely oscillating armature and driver would act on the end of blade 46 to urge contact 47 alternately toward and away from contact 41. But with contact 47 placed substantially at the center of percussion of blade 46 and with screw 56 positioned to stop armature 23 at aposition found by test most greatly to cause the natural vibration of armature 23 and driver 53 to interfere with the natural vibration of the end of blade 46, then there is a minimum amount of contact bounce of contact 47 on contact 41. With a minimum amount of contact bounce in both directions sharp switching definition is secured as required.

All of the parts of the disclosed relay are metal except the ceramic heads 54 on driver 53, the glass ber filled plastic boards 36, 37 and the high temperature resistant coil and wire insulation. It is also to be noted that all of the metal parts which could change in dimensions over a temperature range and could possibly interfere with the operation of the relay are symmetrically arranged to prevent such interference. The relay is continuously operable as calibrated over a very wide range of temperatures.

Having stated some of the objects of my invention, disclosed and described a preferred form in which my invention may be practiced and described its operation,

I claim:

l. A sensitive relay comprising: means forming a magnetic circuit including an armature pivoted on an axis including its center of gravity for rotation thereabout and a pair of air gaps located in said circuit respectively at the two ends of said armature; a first stop means limiting the rotation of said armature in one direction to a first position of maximum air gap length and a second stop means limiting the rotation of said armature in the other direction to a second position of minimum air gap length; means forming an electric circuit adapted when energized to energize said magnetic circuit to rotate said armature in said other direction to said second position; means forming an electric switch having a stationary contact, a movable contact and a resilient switch blade; said switch blade having a fixed end and a free end with said movable contact secured thereon between said ends; said resilient switch blade being positioned permanently to bias said movable contact towards a position of closure on said stationary contact; and said armature including an abutment means positioned in the path of motion of said resilient switch blade only in the direction of the bias of said blade, whereby when said magnetic circuit is energized by said electric circuit said armature will move in said other direction to its said second position while contacting said blade by said abutment means to overcome the bias of said resilient blade to move said blade with said movable contact away from said stationary contact, and thereafter when said magnetic circuit is deenergized said resilient switch blade by its biasing force will be returned to its position of contact of said movable contact on said stationary contact while contacting said abutment means to move said armature in said one direction to its said first position.

2. The relay of claim 1 including a metal container into which said magnetic circuit is press fitted to be undisplaceable in any direction with respect to said container.

3. The relay of claim 1 in which said rst and second stop means are independently adjustably positionable to preset as desired the limits of throw of said armature in its two directions of rotation.

4. The relay of claim 1 in which said magnetic circuit includes a pair of laterally spaced parallel magnetic core pieces bridged at their one similar ends by a magnetic yoke and adapted to be variably magnetically bridged near their other similar ends by said armature, said axis of said armature being parallel to the axes of said core pieces intermediate said axes and in a common plane therewith, each of said core pieces being formed near their said other ends with enlarged sections forming for each of said core pieces a respective. pole face having a face area several times larger than the cross section area of one of said core pieces on either side of` its said enlarged section,v said pole faces being in spaced parallel planes parallel to said axes, said armature. being formed with a pair of spaced parallel pole faces. parallel to and respectively adjacent the pole faces of said core pieces.

5. The relay of claim 4 in which the distance from the axis of said armature to the nearest edge of either ofv said' pole faces of said core pieces is small compared with the distance from the axis of said armature to the farthest edges of said either of said pole faces of said corev pieces.

6. The relay of claim 5 in which said second mentioned distance is at least three times the length of said first mentioned distance.

7. The relay of claim 4 in. which the spaced parallel planes of the, pole faces of said armature are equally spaced from an intermediate plane including the axis of said armature.

8. The relay of claim 4 including a pair of parallel bearing plates spaced by said enlarged pole face sections of said core pieces, each of said bearing plates being press tted at its respective ends on said respective core pieces and said armature being symmetrically journalled in said two bearing plates for free rotation therebetween.

9. The relay of claim 8 including a substantially rigid insulating board secured to both of said bearing plates said stationary contact being secured to saidV board' and said resilient switch blade having its xed end secured to said board at a sufficient angle to the axis of said armature tobias said movable contact on said switch blade towards said stationary contactctoA give said blade a longitudinally arcuate format all times.

10. The relay of claim 8 in which said rst stop means for limiting the rotation of said armature' in said one direction comprises an adjustable screwv` threaded through said rigid insulating board.

11. The relay of claim 4 including a metal container into which said magnetic circuit is pressed fitted, said container being formed at its upper end with a pair of outwardly extending recesses on its inner side, said recesses.y being adapted respectively to receive'the other end of one of said core pieces to support said core piece longitudinally and laterally to render said core pieces undisplaceable in any direction with respect to said con tainer.

12. A relay comprising a magnetic circuit structure and anelectric switch structure, said magnetic circuit structure including a magnetic yoke with a substantially planar surface, a pair of spaced parallel magnetic pole pieces secured to said yoke to extend axially perpendicularly from said planar surface thereof, a pair of spaced: parallel non-magnetic bearing plates spaced from and parallel to said planar surface, each of said plates being perforated with a pair of pole piece holes through which said pole pieces are pressed and a bearing hole equally spaced from said pole pieces in the plane of the axes of said pole pieces, an armature axle between 8. said bearing plates with its ends supported in said bearingholes, au armature between said bearing platesrotat.- ably carried on said axle, an insulating switch blade driver carried on said armature to rotate therewith, said yoke,

said pole pieces and said armature together formingI a.

series magnetic circuit, an electric coil surrounding, a part of saidV magnetic circuit to energize said: circuit when' said c oil` is energized to rotate said armaturein one direction to a preset position of lesser reluctance of said circuit, said armature being rotatable in the other direction to another preset position of greater reluctance when said circuit is deenergized, said electric switch comprising an insulating base board secured to both saidy bearing plates perpendicularly thereto, a pair of spacedsta.-A tionary contacts secured on said base board a, movable contact blade having one end, secured tor said. base board resiliently to bias the other end of said blade. into con,- tact with one of said stationary contacts andthe free end; of said: contact, blade being positioned in the path of said blade driver on said armature to drive saidv blade against its bias. fromV contact with said oner of said stationary con-.- tacts to contact withthe other of said stationary contactsk when said magnetic circuit. is energized and said armature is rotated to` its'positionv of lesser reluctance of said magnetic circuit and whereby said switch blade by` its biasing forceV will be. returned from its contact with` said other stationary contact to contact with said onestationary contact when said magnetic, circuit is deenergized to release said armature tov be counter driven by said switch `blade due to its bias to the preset position of said armature at which said magnetic circuit has its greater reluctance.

13. The relay of claim 12 including a metal. container into. which said magnetic circuit is press fitted, said con,1 tainer being formed at one end withV a pair of, outwardly extending internal recesses adapted respectively: securely to receive` the ends of said pole pieces opposite saidyoke and said container being formed at the other end tightly to secure said yoke laterally and longitudinally in said.

container.

References Cited in the iile of this patent UNITED STATES PATENTS 813,710 Johansson Feb. 27, 1906 1,330,952 Pellet Feb. 17, 1920.` 1,696,170 Leake Dec. 18 1928V 1,763,003 Mead .lune 10, 1930 2,428,784 Cole Oct. 14, 1947y 2,590,996 Miloche Apr. 1, 1952 2,718,568 Sommers Sept. 20, 1955'- 2,767,280 Hall et al. Oct. 1.6, 1956 2,777,922 Horman Jan. 15, 1957v 2,824,189 Zimmer Feb. 18, 1958 FOREIGN PATENTS 572,686 Great Britain Oct. 18, 1945` 708,985 Great Britain May 1-2, 1954 

